1. Field of the Invention
This invention relates to pneumatic converters for converting a pressure signal to a proportional force or displacement signal, or vice versa. More particularly, this invention relates to an improved means for effecting signal conversion by the use of a bellows.
2. Description of the Prior Art
In general, when a pressure is applied to the interior of a bellows, the free end develops a proportional force or displacement. Correspondingly, a force or a displacement may be converted to a pressure by the use of a bellows and a nozzle-flapper mechanism. A pneumatic converter according to the present invention is of such a type.
One of the known prior art converters in general use heretofore for conversion of a pressure to an angular displacement is illustrated in FIG. 1, in which (A) is a front view and (B) is a side view. This unit comprises an L-shaped base S supporting a bellows T fixed at one end thereof to the base. A plate U is rotatably supported on the base by means of a shaft V. The free end of the bellows is maintained in contact with the middle portion of the movable plate U, and a coil spring W is fixed at one end to the base and at its other end is connected to the plate U. The plate carries a pointer X held in place by means of screws Y.
Since the free end Z of the bellows T is bendable through 360 degrees, it becomes necessary for controlling the direction of motion of the pointer X to provide a linear support fulcrum having, for example, a length l as illustrated. Moreover, a base mechanism is needed to secure the bellows T, the coil spring W and so forth, thereby complicating the structure and causing it to be relatively large in size. Consequently, it has been desired to provide an improved bellows unit which is simpler in construction and smaller in size.